Average NFL career length
A number of nuggets about retired numbers around the Major League
Retired number - Wikipedia
List of National Football League retired numbers - Wikipedia
Every MLB team's retired numbers – NBC Sports Chicago
App State to Retire Armanti Edwards' Number 14 - App State Athletics
Best Red Sox players by uniform number
NBA Teams With the Most Retired Numbers
2010-11 Limited Retired Numbers Silver Spotlight #16 Henri Richard
Every MLB team's retired numbers